Field of the Invention
The present invention relates to a printing apparatus.
Description of the Related Art
A printing apparatus in which an energy is applied to a heating element of a thermal head, and printing is carried out by imparting heat to a printing medium by the heating element that has generated heat has been known (For example, Japanese Patent Application Laid-open No. 2001-315374). In a printing apparatus of this type, in a case where an amount of energy (hereinafter, referred to as “applying energy”) to be applied to the heating element is excessively small, there is a possibility that characters printed are faint and patchy. In a case where the amount of applying energy is excessively large, there is a possibility that the characters printed are blurred. In such manner, in a case where the amount of applying energy is inappropriate, there is a possibility that there arises a printing defect.
It has been known that when temperature of the thermal head and temperature of the printing medium which is heated by the heating element at the time of printing are identified, it is possible to correct with high accuracy the amount of applying energy. Practically, it is difficult to detect directly the temperature of the printing medium which is conveyed during printing. For example, in a thermal printer described in Japanese Patent Application Laid-open No. 2001-315374, a thermal head temperature sensor is provided for a thermal head. The thermal head temperature sensor detects the temperature of the thermal head. An ambient temperature sensor is provided for an interior of a main-body case. The ambient temperature sensor detects temperature of the interior of the main-body case instead of the temperature of the printing medium. The thermal printer corrects the amount of applying energy, based on the temperature of the thermal head and the temperature of the interior of the main-body case.